This article is the third of a series about the typical stages and phases of complex engineering projects. Each article takes one stage and describes how Assai supports the requirements and common challenges of that stage – ultimately contributing to the efficient, timely, (cost-)effective and safe delivery of projects. 

Pre-FEED: the third stage in complex engineering projects

Pre-FEED in a nutshell

The pre-FEED stage (pre-FEED is short for preliminary Front-End Engineering Design) – sometimes referred to as ‘Design Basis’ or ‘FEL-2’ phase (if FEL project planning is used) – comes after Conceptual Design and before the FEED stage. It is the final part of conceptual engineering. The selected concept will be defined and detailed further to come to a “design basis” and scope of work (SoW) for FEED.

By the end of pre-FEED, key design decisions have been made, risks are clear and mitigated where needed, there is a clear approach for the execution phase, and cost estimates are more precise (CAPEX +/- 30%). Engineering is often 4 to 8% complete by that time. The duration of this stage varies depending on the nature, location, size and complexity of the project.

Key deliverables and outputs

The two main deliverables of the pre-FEED stage are:

  • Basis of Design (BOD) document (lists the principles, requirements, criteria, assumptions and reasoning on which design calculations and decisions are based)
  • FEED Scope of Work (SoW) (summarizes the project scope, schedule & objectives, interfaces, and the work to be done by the FEED contractor)

Other typical deliverables of the pre-FEED stage include:

  • PFD drawings (Process Flow Diagrams; high-level process overviews, more detailed and formal than a Block Flow Diagram (BFD) from Conceptual Design, and less detailed than a P&ID drawing)
  • Heat and Material Balance, or Heat and Mass Balance (HMB; process overview with major equipment and amount of heating/cooling required, normal operating conditions and flow rates of process streams)
  • Initial P&ID drawings (Piping & Instrumentation Diagrams; process overviews with all crucial equipment, piping and instrumentation)
  • Preliminary plot plan or field architecture
  • Main equipment list
  • Economic assessments (CAPEX, OPEX, ABEX = abandonment expenditure)
  • Start of EIA or ESIA (Environmental (and Social) Impact Assessment)
  • Risk mitigation plans
  • Enhanced project schedule
Scope of work being handed over

The importance of Document Control

During pre-FEED, the number of documents, drawings, people and activities grows rapidly, as seen above. There will be more official document reviews and approvals, often multiple revisions per document, a larger team, perhaps multiple companies, and usually tighter timelines – and thus higher risks of mistakes, inefficiency, re-work and project delays.

This makes it highly beneficial, if not vital, to have a professional eDMS and Document Control business function in place, or to start setting this up now. This needs to be able to accommodate the project’s requirements, standards and procedures. The eDMS should be a reliable central repository where everyone can easily find all latest information, but also have solid Document Control features, such as document numbering and revisioning based on project standards, efficient distribution (standardized and automated), integrated review & approval flows, clear roles & responsibilities, and full traceability. This sets a major step toward the timely and successful completion of the pre-FEED stage.

Our advice: select an eDMS in time! Doing this in the busy FEED stage can lead to a less fit or poorly configured eDMS solution, making this a liability instead of a valuable asset. An eDMS is best implemented during pre-FEED or earlier.

Arno van Vulpen – Assai

How Assai supports pre-FEED

Assai provides out-of-the-box support for all project stages (and operations), with over 30 years of experience. The following Assai features are key in supporting the pre-FEED stage and a paperless office:

  • Powerful document search & folder trees (automated + custom)
  • Easy maintenance of numbering standards and reference data lists
  • Easy preloading of the MDR (Master Document Register)
  • Planning, progress & forecasts at any level: document, work package (WBS) and project
  • Built-in review & approval flows; highly configurable
  • Distribution matrix with (pre-)defined roles & responsibilities
  • Assai Portal for sharing & collaboration with external parties
  • Extensive automation and self-service opportunities
  • E-mail notifications about changes and (new or overdue) actions
  • Easy digital document handover from pre-FEED to FEED
  • Standard reports and dashboards, Power BI reporting
Reporting in Power BI from Assai

Plus, as highlighted in previous articles:

  • Assai provides a proven, reliable, user-friendly and secure “single source of truth”  for all your project deliverables, no matter the project size or complexity. Everything is traceable and can be reported on.
  • Assai Cloud (or on-premises) is a flexible, turnkey solution with full support for engineering projects, operations, maintenance & modifications, and integration options with Digital Twin environments and Common Data Environments (CDE).


We hope you found this article about the pre-FEED stage interesting and useful. Please let us know if you have any questions or feedback, or if you would like to explore with us how Assai could support your project(s).

A short summary of what was discussed in this article:

  • The pre-FEED stage adds more detail to the design concept selected in Conceptual Design. It creates a design basis and scope of work for the FEED stage, so that can be entered with confidence.
  • Pre-FEED generates a wide variety of deliverables and document types, with more formal review & approval cycles, more people, more disciplines and perhaps contractors. It becomes more challenging to stay in control of roles & responsibilities and of what is delivered, planned, or late.
  • At this stage, a specialized eDMS application and Document Control function are not just valuable to have; they are critical success factors (CSF) for optimal and timely completion of this project stage.
  • Many industry leaders worldwide trust Assai as their eDMS solution of choice, which is built on 30+ years of industry experience and best practices. Assai promises true out-of-the-box support for all project stages including pre-FEED and beyond; even into operations, maintenance & modifications, and Digital Twins.

Download the 50+ page PDF!

If you would like to read all articles in a 50+ page PDF which you can print or distribute in your organization, you can download them via the form below:

Previous stage: Conceptual Design

Next stage: FEED

All articles in this series:

Feasibility Study
Conceptual Design
Pre-FEED  (current article)
Detailed Design
Procurement & Fabrication
Construction & Installation

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